/*
  ZynAddSubFX - a software synthesizer

  Analog Filter.h - Several analog filters (lowpass, highpass...)
  Copyright (C) 2002-2005 Nasca Octavian Paul
  Author: Nasca Octavian Paul

  This program is free software; you can redistribute it and/or modify
  it under the terms of version 2 of the GNU General Public License
  as published by the Free Software Foundation.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License (version 2) for more details.

  You should have received a copy of the GNU General Public License (version 2)
  along with this program; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA

*/

#ifndef ANALOG_FILTER_H
#define ANALOG_FILTER_H

#include "Filter_.h"
class AnalogFilter : public Filter_
{
public:
  AnalogFilter(unsigned int sample_rate,
               unsigned char Ftype,
               REALTYPE Ffreq,
               REALTYPE Fq,
               unsigned char Fstages);
  ~AnalogFilter();
  void filterout(REALTYPE *smp, unsigned int sample_count);
  void setfreq(REALTYPE frequency);
  void setfreq_and_q(REALTYPE frequency,REALTYPE q_);
  void setq(REALTYPE q_);

  void settype(int type_);
  void setgain(REALTYPE dBgain);
  void setstages(int stages_);
  void cleanup();

  REALTYPE H(REALTYPE freq);//Obtains the response for a given frequency

private:
  struct fstage{
    REALTYPE c1,c2;
  } x[MAX_FILTER_STAGES+1],y[MAX_FILTER_STAGES+1],
    oldx[MAX_FILTER_STAGES+1],oldy[MAX_FILTER_STAGES+1];

  void singlefilterout(REALTYPE *smp, unsigned int sample_count,
                       fstage &x,fstage &y,
                       REALTYPE *c,REALTYPE *d);
  void computefiltercoefs();

  unsigned int m_samplerate;
  int type;//The type of the filter (LPF1,HPF1,LPF2,HPF2...)
  int stages;//how many times the filter is applied (0->1,1->2,etc.)
  REALTYPE freq;//Frequency given in Hz
  REALTYPE q; //Q factor (resonance or Q factor)
  REALTYPE gain;//the gain of the filter (if are shelf/peak) filters

  int order;//the order of the filter (number of poles)

  REALTYPE c[3],d[3];//coefficients

  REALTYPE oldc[3],oldd[3];//old coefficients(used only if some filter paremeters changes very fast, and it needs interpolation)

  REALTYPE xd[3],yd[3];//used if the filter is applied more times
  int needsinterpolation,firsttime;
  int abovenq;//this is 1 if the frequency is above the nyquist
  int oldabovenq;//if the last time was above nyquist (used to see if it needs interpolation)
};


#endif

